1. Technical Field
The present invention relates to a method for manufacturing an active matrix substrate, an active matrix substrate, an electro-optical device, and an electronic apparatus.
2. Related Art
Along with the popularization of mobile devices such as notebook personal computers, cellular phones, thin-and-light liquid display devices are widely used. This type of liquid crystal display device has a structure in which a liquid crystal layer is sandwiched between an upper substrate and a lower substrate.
An example of the lower substrate (active matrix substrate) is shown in FIG. 19. As shown in FIG. 19, a lower substrate 30 is structured by including a glass substrate P, a gate scan electrode 11 and a source electrode 17 both of which are wired on the glass substrate P so as to be intersected with each other, a drain electrode 14 wired on the glass substrate P, a pixel electrode (ITO) 19 connected to the drain electrode 14, an insulation layer 28 provided between the gate scan electrode 11 and the source electrode 17, and a thin film transistor (TFT) 63 composed of a thin film semiconductor. For forming various metal wirings in the lower substrate 30, a method is employed as exemplified in JP-A-9-171974. In the method, a process is repeated many times in which dry processes and photolithography are combined.
The technique, however, has a drawback in that material costs and administrative costs increase, while a yield rate is hardly increased since the process is carried out many times in which dry processes and photolithographic etching processes are combined. Specifically, the wiring pattern of a thin film is formed by the following manners: a photosensitive material called a resist is coated on a substrate on which a conductive film has been coated in advance; a circuit pattern is irradiated and developed; and the conductive film is etched corresponding to a resist pattern so as to form the wiring pattern. The technique also requires large-scale equipment such as vacuum apparatuses, and has material use efficiency of a few percents, thereby resulting in almost all material being discarded. As a result, it leads to high manufacturing costs. Therefore, reducing the number of processes in which dry processes and photolithographic etching processes are combined is a major issue for liquid crystal display devices required to match the trend lines of lower product costs.